Mexico Primary Could Leave PRI
Winning, Weakened by New Rifts

MEXICO CITY -- It's make or break time for the Institutional Revolutionary Party's fling with internal democracy.

Mexico's ruling party, known as the PRI, holds its first-ever presidential primary on Sunday. If all goes smoothly, it will be in the driver's seat to take the country's presidency yet again in next year's general election. But if the results are muddied by fraud charges, the party could face a devastating internal crisis,...